(a) Field of the Invention
The present invention relates to multifocal contact lenses. More particularly, the invention relates to a hydrophilic contact lens of the composite multifocal type for simultaneous and alternate vision, enabling to correct cases of presbyopia which may be associated with all kinds of ametropia and which enables a person to have a good vision from all distances.
As used in the present specification and claims, the terms "multifocal", "composite", "simultaneous vision" and "alternate" will be defined as follows. Multifocal: lens having more than one focus. The rays passing through the lens are focused at various distances. Composite: the optical zones are of two very different types, spherical and aspherical. Simultaneous vision: correction of vision is available for all distances without requiring a displacement of the lens. Alternate: in reading position, head downwardly inclined, the lens has a tendency to slightly rise towards the upper part of the eye. This displacement enables the use of the second annular zone thereby contributing to vision for reading.
(b) Description of Prior Art
It is known that presently, multifocal contact lenses because of their construction and design, are not satisfactory to most people.